The invention relates to valves in general, and more particularly to improvements in valves with rotary valving elements. Still more particularly, the invention relates to improvements in valves which are especially suited to control the flow of fluids which are conveyed at elevated pressures.
Certain fluids (such as lacquers and paints) exhibit a pronounced tendency to incrustate on the adjacent solid parts and to thereby block the movements of certain parts, e.g., the movements of valving elements in valves which control the flow of paints or lacquers. For example, the rotary valving elements of conventional valves which control the flow of lacquers, paints and like fluids tend to jam when they are supposed to move from closed to open positions or vice versa. Moreover, the passages and channels for the flow of lacquers or paints through conventional valves having rotary valving elements are not readily accessible to permit scraping off the incrustated substances, and such passages and channels exhibit a rather pronounced resistance to the flow of fluids therethrough. Thus, cleaning of and other maintenance work upon conventional valves constitutes a costly and time-consuming operation. In addition, conventional valves are rather bulky and quite expensive. The high initial cost of conventional valves is attributable to the number and complexity of sealing devices which must be employed to prevent leakage of conveyed fluids, especially when the fluids are conveyed at elevated pressures.